Digital imaging is commonly used today in numerous applications. An image sensor for acquiring digital images typically comprises an array of pixels arranged in rows and columns, wherein each pixel comprises a light-sensitive area for detecting light incident on the pixel in order to form an image.
The image sensor may further comprise readout circuitry for reading out image information collected by the pixels and converting the image information to digital domain.
The array of pixels and the readout circuitry may be controlled for controlling acquisition of an image. The pixels in the array may need to be controlled by a sequence of several signals in order to control the pixel to be reset, capture light during an exposure period, and read out the information based on amount of captured light.
Typically, the image sensor may comprise at least one analog-to-digital converter for converting an analog measurement of incident light to a digital value and the image sensor may be controlled such that image information may be read out row by row. The controlling of the image sensor may be provided by a sequencer, which provides an accurate timing of the numerous control signals that needs to be provided to the rows of pixels for controlling exposure times of each row.
The sequencer may need to be very complex, if it is desired to enable different controlling for different regions of interest of the image sensor (such as different exposure times in different regions). If it is desired that the image sensor also or alternatively is to be able to be run in different modes, such as a global shutter mode and a rolling shutter mode, a complexity of the sequencer may be further increased.
In US 2016/0277697, an image sensor is disclosed having a sequencing circuit which comprises a programmable memory containing binary words in which the position i of a bit in a word corresponds to the position i of a respective control signal; and a control signal generation circuit establishing each control signal of position i from the succession of bits of respective position i that are extracted from the memory by a memory controller. The programmable memory allows generating different sequences of control signals. However, the programmable memory requires a large memory capacity in order to enable providing a programming to generate the control signals.